While it is old to utilize a well safety valve for controlling the flow between the inside and outside of a valve, the present invention is directed to various improvements in a hydraulic control safety valve in which (1) the flow of well fluid acts on the valve to tend to close the valve, (2) the valve can be set at deeper depths with variable closing pressures by the use of dual actuating pistons, (3) a hydraulic permanent lockout piston is provided, (4) minimum sealing on the valve closure means is provided to minimize friction, and (5) the valve is short, light and has a minimum number of parts, and (6) wherein the actuating piston and lockout piston may be actuated independently or in combination.